1. Field of the Invention
The present invention relates to a disk drive apparatus that is represented by a hard disk drive, and in particular, to technology for improving a collection efficiency of a dust filter in a disk drive apparatus.
2. Background Art
A hard disk drive that is the most general as data storage means of a computer (hereinafter, an HDD) has the structure of locating one or a plurality of magnetic disk platters in the same shaft and driving the one or plurality of magnetic disk platters by a spindle motor. Reading and writing is performed by a magnetic head which is provided with facing respective surfaces of the magnetic disk, and this magnetic head is driven by an actuator, that is, a voice coil motor (hereinafter, a VCM) in general. The above-described magnetic disk, magnetic head, and actuator are contained in a housing that is called a disk enclosure. The disk enclosure consists of a base made of a shallow-box-like aluminum alloy and a top cover sealing an opening section of the base.
Main technical subjects in HDDs are to improve memory capacity per magnetic disk platter, and to improve reading speed of data, stored in a magnetic disk, and writing speed of data into the magnetic disk. As for the latter, it is possible to improve reading and writing speed of data by shortening seek time when the magnetic head moves to a necessary track on the magnetic disk. Since the magnetic head is driven by a VCM as described above, it is possible to accelerate the seek time by enhancing the performance of this VCM. In order to enhance the performance of the VCM, it is sufficient just to adopt another permanent magnet that configures the VCM and has a stronger magnetic characteristic, or to enlarge a magnetic field applied to the voice coil by making the permanent magnet thicker. Nevertheless, the enhancement of the magnetic characteristic of a permanent magnet is also near to its limit. Furthermore, in an HDD that is requested to be small, there is a limit to make a permanent magnet thicker than a current one.
In addition, by accelerating the rotational speed of a magnetic disk, it is possible to improve the reading and writing speed of data. Nevertheless, if the rotational speed of a magnetic disk is accelerated, a probability that dust collides with a magnetic head becomes higher even if the same number of dust exists in an HDD. This collision may cause a damage of the magnetic head, and magnetic disk. On the other hand, because the floating height of a magnetic head from a magnetic disk is also lowered so as to correspond to capacity expansion of the magnetic disk, there is a possibility of collision even if the dust has small size that has not been a big issue up to now. Therefore, dust reduction in an HDD becomes an important subject.
Because a disk enclosure configuring an HDD consists of a base and a top cover, and an opening section of the base is sealed by the top cover, dust hardly enters into the HDD after the assembly of the HDD. Therefore, dust becoming a problem is mixed inside the disk enclosure in the process of assembling the HDD. The HDD has a catching mechanism to catch this dust.
FIGS. 9 and 10 are perspective views showing the configuration of a disk enclosure 116 configuring a conventional HDD. FIG. 9 shows a condition that a base 112 and a top cover 114 are separated from each other, and FIG. 10 shows a condition that the top cover 114 is mounted on the base 112. In addition, the top cover 114 shown in FIG. 9 is a backside facing the base 112. Furthermore, in FIG. 10, in order that the inside of the base 112 can be observed, the top cover 114 is shown in a transparent condition.
The base 112 has a peripheral wall 112a that is stood around its outer periphery. In an area surrounded by the peripheral wall 112a, there are a disk container 112b containing a disk assembly that consists of a magnetic disk and a spindle motor rotationally driving the magnetic disk, and an actuator container 112c accommodating an actuator mechanism for making a magnetic head seek a track on the magnetic disk. The catching mechanism 113 of dust is located in the outer periphery of the disk container 112b. 
An enlarged top view showing the vicinity of the catching mechanism 113 is shown in FIG. 4. The catching mechanism 113 has a partition wall 113a, stood at a predetermined distance from the peripheral wall 112a of the base 112, and a filter 113b, located between the peripheral wall 112a and partition wall 113a. A catching chamber 113e is formed between the partition wall 113a and peripheral wall 112a, and an inlet 113c is formed in one end of the catching chamber 113e and an outlet 113d is in another end.
Since the magnetic disk turns counterclockwise (shown by a dotted arrow in the figure), a counterclockwise air stream occurs in the disk container 112b. Dust in the HDD floats with this air stream. As for this air stream, because linear velocity caused by the rotation of the magnetic disk becomes larger as going to the outer periphery, dust moves along the peripheral wall 112a. In addition, the dust enters the catching mechanism 113 from the inlet 113c with the air stream, and is caught by the filter 113b. The air stream after the dust being caught is exhausted from the outlet 113d. Although the dust in the HDD is caught in this manner, it is requested to improve a collection efficiency of the filter 113b in connection with accelerating the rotation speed of the magnetic disk. Then, the present invention is intended to improve a dust collection efficiency in a disk drive apparatus represented by an HDD.
As an index for measuring the collection efficiency in the filter 113b, there is the pressure drop before and after the filter 113b. This is an evaluation method adopted also in IDEMA (International Disk Drive Equipment Material Association). Thus, in FIG. 4, let pressure before the filter 113b be Pf and let pressure after the filter 113b be Pr. The larger the pressure drop obtained from Pf-Pr is, the more volume of air passes the filter 113b. Assuming that dust is included uniformly in the air passing the catching mechanism 113, that more volume of air passes the filter 113b means that more volume of dust collides against and is caught by the filter 113b. Therefore, the present inventor investigated to enlarge the pressure drop (L) obtained from Pf-Pr.
It is possible to enlarge the pressure drop (L) by increasing Pf or decreasing Pr. Then, first, a review about structure of the catching mechanism 113 was performed about whether Pr could be increased. In order to increase Pr, it is effective to enhance airtightness in the catching chamber 113e that is a space formed by the partition wall 113a, filter 113b, peripheral wall 112a, and top cover 114. Nevertheless, it is confirmed that airtightness of the catching chamber 113e is not enough in the catching mechanism 113 of the conventional HDD.
As shown in FIGS. 9 and 10, a gasket 115 is provided in a back face of the top cover 114, and when the top cover 114 is mounted on the base 112, the gasket 115 is pressed on a top face of the peripheral wall 112a in the base 112 to secure airtightness against the outside. Here, a partial cross section of the catching mechanism 113 is shown in FIG. 5A, and according to the figure, a gap is formed between the partition wall 113a and top cover 114. This is because there was concern about not being able to secure the airtightness in the HDD because of the lack of contact pressure of the gasket 115 and peripheral wall 112a if the partition wall 113a contacts to the top cover 114. In general, although the base 112 consists of aluminum alloy formed by die casting, it is difficult to form highly precise parts by die casting. Owing to that, conventionally, the base 112 has been designed so that the contact of the partition wall 113a and top cover 114 is surely avoided. Therefore, for example, in such an aspect that is shown by a solid arrow in FIG. 4, an air stream leaks out from the catching chamber 113e. As described above, a gap between the partition wall 113a and top cover 114 becomes a large factor which obstructs the enhancement of airtightness in the catching chamber 113e. Nevertheless, that a gap between the partition wall 113a and top cover 114 existed was not a technical issue in HDDs before the rotational speed of a magnetic disk was highly accelerated.
Then, the present inventor planed to form such a wall that completely isolates the disk container 112b from the catching chamber 113e except the inlet 113c and outlet 113d. Therefore, the present invention is a disk drive apparatus characterized in comprising: a disk-like medium that is rotationally driven with a rotation axis as a center and stores data; a medium container accommodating the disk-like medium; a wall isolating a catching chamber from the medium container; an inlet introducing an air stream occurring by rotation driving of the disk-like medium; an outlet exhausting the air stream; and a catching chamber catching dust included in the air stream. The wall of the present invention can be implemented by providing a gasket, which is mounted with press on the partition wall 113a, on the top cover 114. Thus, it is possible to configure the wall by the partition wall 113a and gasket newly provided. Nevertheless, this is an example for easier comprehension of the wall, and hence, this does not become a ground of limiting the present invention.
In a disk drive apparatus of the present invention, by providing the wall, it becomes possible to prevent air streams from leaking from the catching chamber to the medium container. Therefore, the front pressure Pf of the filter 113b becomes large, and hence it is possible to increase the pressure loss (L).
In addition, in a disk drive apparatus of the present invention, the catching chamber can be located in an outer periphery of the medium container. This is because, in a disk drive apparatus, for example, an HDD, an air stream occurs by the rotation of a magnetic disk, and since the linear velocity of the air stream becomes larger as going to an outer peripheral area of a magnetic disk container, it is desirable in view of a collection efficiency to provide the catching chamber in the area. Moreover, in a disk drive apparatus of the present invention, a filter catching the dust can be provided between the inlet and outlet in the catching chamber.
A disk drive apparatus of the present invention can be applied to an HDD. Therefore, the present invention provides a hard disk drive characterized in comprising: a disk assembly that consists of a disk-like medium, magnetically storing data, and a spindle motor, rotationally driving the disk-like medium; an actuator that has a magnetic head to store data in and reproduce data from the disk-like medium, and that makes the magnetic head seek the disk-like medium and rotates the magnetic head with a pivot as a center; a base that accommodates the disk assembly and provides an approximately cylindrical disk container, and around which a peripheral wall is provided, a catching chamber which has an inlet and an outlet, communicating with the disk container, and a partition wall partitioning the disk container from the inlet and outlet; a top cover functioning as a lid of the base; a first gasket existing between the top cover and peripheral wall of the base; and a second gasket existing between the top cover and partition wall of the catching chamber.
Because the hard disk drive of the present invention has the second gasket between the partition wall and top cover of the catching chamber, insulation between the disk container and catching chamber is realized by the partition wall and gasket. Owing to this, it is possible to prevent an air stream from leaking from the catching chamber to the disk container.
In the present invention, although a wall can be formed by making a partition wall high to a top cover, as described above, it is not easy to strictly control the height of the partition wall. Therefore, it is desirable in the present invention to form a gasket, consisting of an elastic body, as a part of a component of the wall.
In a hard disk drive of the present invention, it is possible to form the first gasket and second gasket in one piece. Hence it is possible to reduce a manufacturing cost of the gaskets, and to perform mounting operation to the top cover only once. The gasket of the present invention can be made of, for example, rubber such as fluororubber. In that case, it is possible to form the gasket with unifying the first gasket and second gasket by forming a cavity obtained by combining the first gasket and second gasket.
In a hard disk drive of the present invention, it is desirable that the height of the partition wall is lower than the height of the peripheral wall. Although this will be described in detail in xe2x80x9cPreferred embodimentxe2x80x9d, it is because it is effective to keep airtightness by the first gasket if it is assumed that the first gasket and second gasket are equal in thickness.
The present invention provides the above-described gasket used in a disk drive apparatus, or a hard disk drive. A gasket that is mounted in a disk drive apparatus whose inside is partitioned into a plurality of partitions, and the gasket is characterized in comprising: a first gasket section forming a loop for keeping airtightness of the disk drive apparatus against the outside; and a second gasket section that configures walls between the plurality of partitions inside the disk drive apparatus and is unified with the first gasket section.
In a gasket of the present invention, it is possible that the disk drive apparatus comprises a medium container accommodating a disk-like medium, and a catching chamber catching dust in the disk drive apparatus, and that the second gasket section keeps airtightness between the medium container and catching chamber. Furthermore, in a gasket of the present invention, it is desirable that the height of the second gasket section is lower than the height of the first gasket section.
The present invention provides a top cover that configures a disk enclosure of a hard disk drive with a box-like base, the top cover comprising: a flat cover body; a looped first gasket that is fixed around the cover body and is to keep airtightness of the disk enclosure from the outside; and a second gasket that is fixed to the cover body in a loop of the first gasket, and configures a wall in the disk enclosure.